1. Field of the Invention
The present invention relates to a modular jack, and more particularly to a modular jack which is to be mounted on a circuit board of an electronic appliance such as a telephone, a facsimile or the like to connect the electronic appliance with a telephone line.
2. Description of Related Art
In an electronic appliance which employs a modular jack, in order to eliminate noise, conventionally a filter such as a three-terminal capacitor or a common mode choke coil is provided on a circuit board separately from the modular jack. However, providing a filter and a modular jack separately complicates the production of the circuit board, and the produced circuit board will be large.
In the light of these problems, we disclosed in U.S. Pat. No. 5,015,204 a modular jack containing a common mode choke coil which comprises a ring-shaped core and two coils coiled thereon. One end of the coils is made to be a contactor with a plug, and the other end is made to be a terminal used for mounting of the modular jack on a circuit board. The modular jack has advantages that it functions as a noise suppressor because it contains a common mode choke coil and that it is compact because a coil, a contactor and a terminal are made into a unit. However, the modular jack has the following drawbacks. In order to increase the number of circuits, more space for more cores is required, and the modular jack cannot be made compact. The electrode pitch of a circuit board is ordinarily 1.02 mm, but the terminal pitch of the modular jack is more than 1.02 mm because of the cores. Therefore, a newly designed circuit board is required.
Further, we disclosed in U.S. Pat. No. 5,069,641 a modular jack which contains a printed board having chip type filter elements in a housing.